Monoamine oxidase B inhibitors, processes for their preparation and use thereof

ABSTRACT

Novel monoamine oxidase B inhibitors of formula (I), wherein R 1  ═H, an optionally substituted benzyloxy or phenylethoxy group; p=0-3; R 3  ═H, a CN, OH, CCH group, a C 1  -C 3  alkoxy-carbonyl group, or a C 1  -C 3  alkylated cyanomethyl group; R 2  ═H or a C 1  -C 3  alkyl group; n=0 or 1; if n=0, R 4  is a C 1  -C 3  alkyl group or a C 1  -C 3  alkoxy group, while if n=1, y=1 and R 4  is a C 1  -C 3  alkyl group, a C 1  -C 3  alkoxy group or a phenyl group. The invention also concerns processes for the preparation of said novel inhibitors and the therapeutic use thereof. ##STR1##

This application is a 371 of PCT/Fr95/0006, filed Jan. 19, 1995.

The subject of the present invention is monoamine oxidase B inhibitors,processes for their preparation and their use in therapy.

Monoamine oxidases (MAO) are enzymes, located mainly in the outermembrane of the mitochondria and responsible for metabolizing a numberof monoamines acting as neurotransmitters in mammals.

In the human body, the principal monoamines which are deaminated by MAOsbelong either to the indole series: tryptamine and 5-hydroxytryptamineor serotonin, or to the aromatic amino acid series: tyramine andcatecholamines such as dopamine, noradrenaline and adrenaline.

Two principal forms of MAO can be currently identified in the body: an Aform which is thought to convert more particularly serotonin andnoradrenaline, and a B form whose preferred substrates are benzylamineand phenylethylamine, both forms converting, in a roughly equivalentmanner, dopamine, tyramine and tryptamine.

Some organs appear to express only one of the two enzymes whereas bothforms are simultaneously present in other tissues such as the liver orthe brain.

Given that the hypotheses relating to the bio-chemical mechanisms ofdepression involve certain mono-amines such as serotonin andcatecholamines, it was proposed, from 1957, to use MAO inhibitors in thetreatment of this pathology.

So far, three generations of MAO inhibitors have appeared in succession:

1/ So-called "mixed" and "irreversible" inhibitors:

The major one among them is phenelzine (NARDELZINE®) and iproniazide(MARSILID®).

The structure common to these inhibitors is a hydrazine group.

They are termed "mixed" because they inhibit both forms of MAO. They aretermed "irreversible" because they form a covalent bond with theseenzymes which results in an irreversible inactivation of said enzymeswhich comes to an end only well after stopping the treatment, when thenewly synthesized enzymes have taken over (15 to 21 days). In addition,they are responsible for a modification of blood pressure resulting inundesirable blood pressure disorders: hypotension, vertigo, dizziness,hypothymic and even syncopal tendencies.

2/ "Selective" and "irreversible" inhibitors:

This second generation of MAOIs includes three families of compoundswhich are the arylhydrazines, the propargylics and thecyclopropylamines.

These compounds preferably act on either form of the MAOS. Thus, forexample, among the propargylic inhibitors, clorgyline and pargylineinhibit MAO A whereas deprenyl acts on MAO B.

It should however be noted that, although inhibiting the MAOs, some ofthese compounds, such as pargyline and deprenyl, lack antidepressanteffects and have been indicated in the treatment of Parkinson's disease,in combination with L-dopa.

In addition, all these compounds act by first binding noncovalently tothe MAOs, and then by forming with them irreversible covalent complexes,limiting their manageability because of the persistence of their actionwell after stopping the treatment.

Thus, for example, a general anesthetic can only be envisaged in apatient treated with this type of MAOI after a period of about threeweeks after stopping the treatment.

3/ "Selective" and "reversible" inhbitors:

These third-generation inhibitors include:

derivatives of harmala, alkaloids from Peganum harmala, which areselective and reversible inhibitors of MAO A, with a very short durationof action;

phenylalkylamines, which are selective inhibitors of MAO A;

derivatives of oxazolidinones, which are selective inhibitors of MAO Aand which have as principal representative toloxatone (HUMORYL®) Thesecompounds are described in EP 0,424,243, EP 0,428,421 and EP 0,511,031.

Although the use of these compounds represents a definite advance intherapy because of their rapidly reversible activity (in less than 24hours), some physiopathological studies relating to senile dementia andAlzheimer's disease appear to show a most special advantage in using theB MAOIs.

Indeed, in these pathologies, a high increase in the MAO B/MAO A ratiois observed which is accompanied by an increase in a destructiveactivity of the MAOs. The decrease in the number of neurons producingdopamine linked with cellular aging also contributes to thisphysiological phenomenon. A possible inhibition of MAO B by selectiveand reversible products should make it possible to reequilibrate theratio between the two forms of enzyme in favor of MAO A, and thus toimprove the condition of the subjects.

Patent Applications EP 0,348,257 and WO 91/08201 propose derivatives of4-(arylmethyloxy)phenyldiazole, essentially represented by tetrazoles,which appear to exhibit an anti-MAO activity which is selective againstMAO B. However, no information is available, as regards the compoundsdescribed in this application, on the reversibility of their activity,or a decline both from the pharmacological and toxicological point ofview.

The applicants consequently set themselves the objective of providingnovel inhibitors of MAO B exhibiting both selectivity and reversibilitytoward MAO B, conferring on them great therapeutic manageability.

The subject of the present invention is therefore the use of a compoundcorresponding to the following formula (I): ##STR2## in which: R₁represents a hydrogen atom, a benzyloxy group or a phenylethoxy groupwhose phenyl ring is optionally substituted;

p is an integer from 0 to 3;

R₃ represents a hydrogen atom, a CN group, a hydroxyl group, a CCHgroup, a (C₁ -C₃ alkoxy)carbonyl group or a C₁ -C₃ alkylated cyanomethylgroup;

R₂ represents a hydrogen atom or a C₁ -C₃ alkyl group;

n is equal to 0 or 1, in which case:

if n=0, R₄ represents a C₁ -C₃ alkyl group or a C₁ -C₃ alkoxy group;whereas

if n=1, y=1 and R₄ represents a C₁ -C₃ alkyl group, a C₁ -C₃ alkoxygroup or a phenyl group;

for the preparation of a medicinal product having a monoamine oxidase Binhibiting activity.

The compounds of formula (I) as defined above include their variousisomers.

In the preceding text and in the text which follows, the expression "C₁-C₃ alkyl" designates hydrocarbon groups comprising 1 to 3 carbon atoms,namely methyl, ethyl, n-propyl and i-propyl; the expression "C₁ -C₃alkoxy" corresponds to the formula O-(C₁ -C₃ alkyl); the expression "(C₁-C₃ alkoxy)carbonyl" represents a formula COO-(C₁ -C₃ alkyl); the termhalogen designates chlorine, fluorine, bromine or iodine.

The compounds of formula (I), as defined above, are particularly usefulfor the preparation of a medicinal product having a monoamine oxidase Binhibiting activity because they are capable of inhibiting MAO B bothselectively and reversibly while lacking toxic effects.

For this, they may be used alone or in combination, optionally with oneor more other active ingredients and/or adjuvants which arepharmaceutically compatible.

Preferably, R₁ represents a benzyloxy group whose phenyl ring isoptionally substituted with one or more halogen atoms and/or one or moreNO₂ groups and/or one or more C₁ -C₃ alkyl groups and/or one or more C₁-C₃ alkoxy groups.

Among the compounds of formula (I), some have already been described asbeing capable of having therapeutic applications. However, these relateto the treatment of tuberculosis (STRUMILLO and GRUDZINSKI, Acta Pol.Pharm., 1971, 28, 247-251) and the treatment of rhinopharyngeal viralconditions (U.S. Pat. No. 3,867,425) in which monoamine oxidase Binhibition is not at all sought.

The subject of the invention is therefore also novel medicinal productswhich comprise at least one active ingredient corresponding to one ofthe following specific formulae: ##STR3## in which: R₁ represents ahydrogen atom, a benzyloxy group or a phenylethoxy group whose phenylring is optionally substituted, provided that R₁ is different from ahydrogen atom in the specific formula (I-e);

p is an integer from 0 to 3; and

R₃ represents a CN group, an OH group, a CCH group, a (C₁ -C₃alkoxy)carbonyl group or a C₁ -C₃ alkylated cyano-methyl group.

These medicinal products find application especially in the treatment ofconditions in which lacuna! inhibition of monoamine oxidase B such asfor example depressive syndromes.

Among the medicinal products in accordance with the invention, there arepreferred especially those comprising, as active ingredient(s), thecompounds of specific formulae (I-a), (I-b), (I-c), (I-d) and (I-e),presented in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Code No. R.sub.1        p         R.sub.3                                     ______________________________________                                        I-a1     H              2         CN                                          I-a2     benzyloxy      2         CN                                          I-a2.1   (4-methylbenzyl)oxy                                                                          2         CN                                          I-a2.2   (4-nitrobenzyl)oxy                                                                           2         CN                                          I-a2.3   (4-chlorobenzyl)oxy                                                                          2         CN                                          I-a2.4   (4-methoxybenzyl)oxy                                                                         2         CN                                          I-a2.5   (2,4-dichlorobenzyl)oxy                                                                      2         CN                                          I-a2.6   (2-chlorobenzyl)oxy                                                                          2         CN                                          I-a3     H              2         OH                                          I-a4     benzyloxy      2         OH                                          I-a5     benzyloxy      2         COOCH.sub.3                                 I-a6     phenylethoxy   2         CN                                          I-a7     benzyloxy      1         CH--CN                                                                        |                                                                    CH.sub.3                                    I-a8     benzyloxy      1         CN                                          I-a9     benzyloxy      3         CN                                          I-a10    benzyloxy      1         CCH                                         I-b1     H              2         CN                                          I-b2     benzyloxy      2         CN                                          I-b3     H              2         OH                                          I-b4     benzyloxy      2         OH                                          I-c1     H              2         CN                                          I-c2     benzyloxy      2         CN                                          I-c3     H              2         OH                                          I-c4     benzyloxy      2         OH                                          I-d1     H              2         CN                                          I-d2     benzyloxy      2         CN                                          I-e1     benzyloxy      2         CN                                          ______________________________________                                    

In a preferred embodiment of a medicinal product in accordance with theinvention, the latter comprises, as active ingredient,4-(benzyloxy)benzaldehydeacetyl-(2-cyanoethyl)hydrazone (compound I-a2).

Among the compounds corresponding to the specific formulae (I-a), (I-b),(I-c), (I-d) and (I-e), some have already been described, either assunscreens (U.S. Pat. No. 3,419,659), or as products resulting from theacylation of urea (NOVACEK, Collect. Czech. Chem. Commun., 1967 32,1712-1718) or alternatively as pesticides (GADZHIEV and BUDAGOV, Azerb.Khim. Zh., 1975, 5, 47-48).

The subject of the invention is therefore also new compounds whichcorrespond to the following specific formulae: ##STR4## in which: R₁represents a hydrogen atom, a benzyloxy group or a phenylethoxy groupwhose phenyl ring is optionally substituted, provided that R₁ isdifferent from a hydrogen atom in the specific formula (I-e);

p is an integer from 0 to 3; and

R₃ represents a CN group, an OH group, a CCE group, a (C₁ -C₃alkoxy)carbonyl group or a C₁ -C₃ alkylated cyanomethyl group.

The subject of the present invention is, moreover, a process for thepreparation of a compound of specific formula (I-d) as defined above,which comprises:

1) a condensation reaction between an aromatic aldehyde of formula:##STR5## in which: R₁ represents a hydrogen atom, a benzyloxy orphenylethoxy group whose phenyl ring is optionally substituted; and ahydrazine of formula: NH₂ --NH--(CH₂)_(p) -R₃

in which:

p is an integer from 0 to 3;

R₃ represents a CN group, an OH group, a CCH group, a (C₁ -C₃alkoxy)carbonyl group or a C₁ -C₃ alkylated cyanomethyl group;

2) a reaction of acylation of the product derived from reaction 1) bymeans of a reagent such as phenyl isocyanate.

Moreover, all the compounds of formula (I) can be obtained by thisprocess.

Thus, for example, for the preparation of the compounds of specificformulae (I-a) and (I-b), the acylation of the product derived fromreaction 1) (condensation reaction between the aromatic aldehyde andhydrazine) is performed by means of a reagent of formula: R₄ --CO--Cl inwhich R₄ represents a methyl group or an ethoxy group whereas for thepreparation of the compounds corresponding to the specific formula(I-c), the same acylation reaction is performed by means of methylisocyanate.

The subject of the invention is also a process for the preparation of acompound of specific formula (I-e), which process comprises:

1) a condensation reaction between an aromatic aldehyde of formula:##STR6## in which: R₁ represents a benzyloxy or phenylethoxy group whosephenyl ring is optionally substituted; and:

* either a hydrazine of formula: NH₂ --NH--(CH₂)_(p) --R₃ in which:

p is a integer from 0 to 3;

R₃ represents a CN group, an OH group, a CCH group, a (C₁ -C₃alkoxy)carbonyl group or a C₁ -C₃ alkylated cyanomethyl group;

* or the hydrazine of formula: NH₂ --NH--CO--CH₃ 2) a reaction:

* either for acylation of the product derived from reaction 1) by areagent such as acetyl chloride;

* or for alkylation of the product derived from reaction 1) by a reagentof formula: Hal--(CH₂)_(p) --C.tbd.Z

in which:

p is an integer from 0 to 3;

Hal represents a halogen atom;

Z represents a CH group or a nitrogen atom, or by a reagent of formula:Br--(CH₂)_(p) --COO--(C₁ -C₃ alkyl)

in which p is an integer from 0 to 3.

Advantageously, the alkylation reaction is performed with a reagentchosen from bromoacetonitrile, 4-bromobutyronitrile, propargyl bromideor methyl 3-bromopropionate in the presence of one or more solventschosen from anhydrous pyridine, anhydrous ethyl acetate, anhydrousbenzene or acetic acid.

The subject of the invention is finally a process for the treatment ofconditions in which inhibition of monoamine oxidase B is desired, whichprocess consists in administering to a human or animal host an effectivequantity of at least one compound of formula (I) as defined above.

In addition to the preceding features, the invention also comprisesother features which will emerge from the description which will follow,made by way of examples and with reference to the accompanying drawingin which:

FIG. 1 represents a calibration series to determine the proteinconcentration of a mitochondrial suspension;

FIG. 2 illustrates the inhibitory activity of the compound (I-a2) towardMAO A and MAO B;

FIG. 3 illustrates the inhibitory activity of the compound (I-a4) towardMAO A and MAO B;

FIG. 4 illustrates, in the form of histograms, the reversibility of theinhibitory activity of the compound (I-a2) toward MAO B.

It should be clearly understood, however, that these examples are givensolely by way of illustrations of the subject of the invention and donot constitute in any manner a limitation thereto.

EXAMPLES Example 1: Preparation of the compound (I-a1): Benzaldehydeacetyl(2-cyanoethyl)hydrazone

1.1 Preparation of benzaldehyde (2-cyanoethyl)hydrazone:

Benzaldehyde (2-cyanoethyl)hydrazone is prepared by condensation ofbenzaldehyde with (2-cyanoethyl)hydrazine according to the followingprocedure:

10⁻² moles of (2-cyanoethyl)hydrazine are added to a solution containing10⁻² moles of benzaldehyde in 20 ml of ethanol. The reaction is leftunder reflux for 30 minutes. At the end of the reaction, the mixture iscooled. After evaporation of the solvents, the product obtained is inthe form of an extremely unstable oil. The crude reaction yield is 81%.

(2-Cyanoethyl)hydrazine can be obtained by a MICHAEL reaction (HOFFMANV. and JACOBI B., Chemical Abstracts, Vol. 28, p 5473, 1934), that is tosay by the action of hydrazine in excess on one mole of acrylonitrile inethanol.

1.2 Acylation of benzaldehyde (2-cyanoethyl)hydrazone with acetylchloride:

0.78 g (10⁻² moles) of acetyl chloride is added dropwise to a solutioncontaining 10⁻² moles of benzaldehyde (2-cyanoethyl)hydrazone and 0.79 g(10⁻² moles) of anhydrous pyridine in 20 ml of anhydrous ethyl acetate,with stirring in the cold.

The mixture is slowly heated to reflux temperature and left stirring for2 hours, and then filtered hot. After cooling the filtrate, the productcrystallizes. It is filtered. An additional quantity of the latter isobtained by evaporation of the filtrate. The product obtained at the endof the reaction is washed with 10 ml of water and then dried andrecrystallized from ethanol. The product has a melting point equal to109° C. The reaction yield is 54%.

Example 2: Preparation of the compound (I-a2): 4-(Benzyloxy)benzaldehydeacetyl(2-cyanoethyl)hydrazone

2.1 Preparation of 4- (benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone:

4-(benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone is prepared bycondensation of 4-(benzyloxy)benzaldehyde with (2-cyanoethyl)hydrazineaccording to the following procedure:

10⁻² moles of (2-cyanoethyl)hydrazine are added to a solution containing10⁻² moles of 4-(benzyloxy)benzaldehyde in 20 ml of ethanol. Thereaction is left under reflux for 30 minutes. At the end of thereaction, the product precipitates. After filtration, it is recoveredand recrystallized twice from ethanol. The reaction yield is 86%.

2.2 Acylation of 4-(benzylozy)benzaldehyde (2-cyanoethyl)hydrazone withacetyl chloride:

This acylation reaction is carried out according to a procedureidentical to that described in 1.2 of Example 1 above, starting with, onthe one hand, a solution containing 10⁻² moles of4-(benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone and 0.79 g (10⁻²moles) of anhydrous pyridine in 20 ml of anhydrous ethyl acetate and, onthe other hand, 0.78 g (10⁻² moles) of acetyl chloride. It makes itpossible to obtain the compound (I a2) with a yield of 50%. It has amelting point of 150° C.

Example 3: Preparation of the compound (I-a3): Benzaldehydeacetyl(2-hydroxyethyl)hydrazone

3.1 Preparation of benzaldehyde (2-hydroxyethyl)hydrazone:

Benzaldehyde (2-hydroxyethyl)hydrazone is prepared by condensation ofbenzaldehyde with (2-hydroxyethyl)hydrazine according to the followingprocedure: 10⁻² moles of (2-hydroxyethyl)hydrazine are added to asolution containing 10⁻² moles of benzaldehyde in 20 ml of ethanol. Thereaction is left under reflux for 30 minutes. The mixture is thencooled. The solvents are removed by evaporation. The product obtained isan extremely unstable oil. The crude reaction yield is 97%.

(2-hydroxyethyl)hydrazine is a product marketed by ALDRICH.

3.2 Acylation of benzaldehyde (2-hydroxyethyl)hydrazone with acetylchloride:

0.78 g (10⁻² moles) of acetyl chloride is added dropwise to a solutioncontaining 10⁻² moles of benzaldehyde (2-hydroxyethyl)hydrazone and 0.79g (10⁻² moles) of anhydrous pyridine in 20 ml of anhydrous ethylacetate, with stirring in the cold.

The reaction mixture is left at 0° C., with stirring, for 2 hours untilit is filtered. The product obtained at the end of the reaction iswashed with 10 ml of water and then dried and recrystallized fromethanol. The reaction yield is 34%. The product has a melting point of110° C.

Example 4: Preparation of the compound (I-a4): 4-(Benzyloxy)benzaldehyde acetyl(2-hydroxyethyl)hydrazone

4.1 Preparation of (4-benzylozy)benzaldehyde (2-hydroxyethyl)hydrazone:

4-(benzyloxy)benzaldehyde (2-hydroxyethyl)hydrazone is obtained bycondensation of 4-(benzyloxy)benzaldehyde with (2-hydroxyethyl)hydrazineby reacting, for example, a solution containing 10⁻² moles of(4-benzyloxy)benzaldehyde in 20 ml of ethanol with 10⁻² moles of(2-hydroxyethyl)hydrazine. The reaction is left at reflux for 30minutes, at the end of which the mixture is cooled and the hydrazoneobtained precipitates. After filtration, it is recovered andrecrystallized twice from ethanol. It has a melting point of 91° C. Thereaction yield is 79%.

4.2 Acylation of 4-(benzyloxy)benzaldehyde (2-hydroxyethyl)hydrazonewith acetyl chloride:

It is carried out according to a procedure identical to that describedin point 3.2 of Example 3 above, starting, on the one hand, with asolution containing 10⁻² moles of 4-(benzyloxy)benzaldehyde(2-hydroxyethyl)hydrazone and 0.79 g (10⁻² moles) of anhydrous pyridinein 200 ml of anhydrous ethyl acetate and, on the other hand, 0.78 g(10⁻² moles) of acetyl chloride.

It makes it possible to obtain the compound (I a4) with a yield of 38%.It has a melting point of 131° C.

Example 5: Preparation of the compound (I-a2.6): 4-(2-Chlorobenzyl)oxy!benzaldehyde acetyl(2-cyanoethyl)hydrazone

The compound (I-a2.6) is obtained by an alkylation reaction in situperformed according to the following procedure:

0.43 g (5.1×10⁻³ moles) of 2-(cyanoethyl)hydrazine is added, at roomtemperature, with stirring, to a solution of 5×10⁻³ moles of 4-(2-chlorobenzyl)oxy!benzaldehyde in 20 ml of anhydrous benzene. Thereaction mixture is heated to reflux temperature and the water formedduring the reaction is removed by azeotropic distillation. The solutionis then adjusted to 10° C. and 0.40 g (5.1×10⁻³ moles) of anhydrouspyridine and 0.39 g (5.1×! 10⁻³ moles) of acetyl chloride are addedsuccessively. The mixture is left stirring at room temperature for 30minutes. The benzene is then removed by evaporation under vacuum. Theresidue obtained is dissolved in 100 ml of dichloromethane and theresulting organic phase is washed three times with water. It is thendried over magnesium sulfate and then evaporated. The residue iscrystallized from ethanol. It has a melting point of 142° C. Thereaction yield is 51%.

Example 6: Preparation of the compound (I-a2.5): 4-(2,4-Dichlorobenzyl)oxy!benzaldehyde acetyl(2-cyanoethyl)hydrazone

The compound (I-a2.5) is prepared according to a procedure identical tothat described in Example 5, from 4-(2,4-dichlorobenzyl)oxy!benzaldehyde and 2-(cyanoethyl)hydrazine.

The compound (I-a2.5) has a melting point of 137° C. The reaction yieldis 38%.

Example 7: Preparation of the compound (I-a6):4-(2-Phenylethozy)benzaldehyde acetyl(2-cyanoethyl)hydrazone

The compound (I-a6) is prepared according to a procedure identical tothat described in Example 5, from 4-(2-phenylethoxy)benzaldehyde and2-(cyanoethyl)hydrazine. It has a melting point of 129° C. The reactionyield is 55%.

Example 8: Preparation of the compound (I-a7):

4-(Benzyloxy)benzaldehydeacetyl(2-cyanopropyl)hydrazone

0.64 g (5.1×10⁻³ moles) of 2-(cyanopropyl)hydrazine is added, at roomtemperature and with stirring, to a solution of 5×10⁻³ moles of4-(benzyloxy)benzaldehyde in 20 ml of anhydrous benzene. The reactionmixture is heated to reflux temperature and the water formed during thereaction is removed by azeotropic distillation. The solution is thenadjusted to 10° C. and 0.40 g (5.1×10⁻³ moles) of anhydrous pyridine and0.39 g (5.1×10⁻³ moles) of acetyl chloride are added successively. Themixture is left stirring at room temperature for 30 minutes. The benzeneis then removed by evaporation under vacuum. The residue obtained isdissolved in 100 ml of dichloromethane and the resulting organic phaseis washed three times with water. It is then dried over magnesiumsulfate and then evaporated. The residue is recrystallized from ethanol.It has a melting point of 106° C. The reaction yield is 42%.

Example 9: Preparation of the compound (I-a5): 4-(Benzyloxy)benzaldehydeacetyl (2 -methoxycarbonylethyl) hydrazone

9.1 Preparation of 4-(benzyloxy)benzaldehyde acetylhydrazone:

A solution of 10⁻² moles of acetylhydrazine (0.74 g) in 20 ml of ethanolis added to 10⁻² moles of 4-(benzyloxy)benzaldehyde (2.12 g) in 20 ml ofethanol. The reaction mixture is heated to reflux temperature for 90minutes, at the end of which the solution is slowly adjusted to 0° C.The product obtained precipitates. It is filtered, drained andrecrystallized from ethanol. Melting point: 170° C. Reaction yield: 76%.

9.2 Alkylation of 4-(benzyloxy)benzaldehyde acetylhydrazone:

A solution of 5×10⁻³ moles of 4-(benzyloxy)benzaldehyde acetylhydrazone(1.34 g) in 5 ml of anhydrous DMF is added to 5×10⁻³ moles of sodiumhydride (0.12 g) in suspension in 10 ml of anhydrous DMF. The reactionmixture is heated slowly on a water bath at 80° C. for 30 minutes. Aftercooling, a solution containing 0.85 g (5.1×10⁻³ moles) of methyl3-bromopropionate in 5 ml of DMF is slowly added to the mixture. Thelatter is stirred for one hour at room temperature, then it is pouredinto 100 ml of ice-cold water. A product precipitates. After standingfor 30 minutes, it is filtered, subjected to draining, at the end ofwhich it is chromatographed on a MACHEREY-NAGEL silica gel 60(0.04-0.063 ml) using a mixture of ethyl acetate and dichloromethane(1/9) as eluent. The oil obtained precipitates. The compound (I-a5) isslowly recrystallized from ether. Its melting point is 170° C. Thereaction yield is 11%.

Example 10: Preparation of the compound (I-a8):

4-(Benzylozy)benzaldehyde acetyl(cyanomethyl)hydrazone

The compound (1-a8) is obtained by an alkylation reaction of4-(benzyloxy)benzaldehyde acetylhydrazone, prepared in accordance withpoint 9.1 of Example 9 above, with bromoacetonitrile.

The alkylation with bromoacetonitrile is performed according to thefollowing procedure: a solution of 5×10⁻³ moles of4-(benzyloxy)benzaldehyde acetylhydrazone (1.34 g) in 5 ml of anhydrousDMF is added to 5×10⁻³ moles of sodium hydride (0.12 g) in suspension in10 ml of anhydrous DMF. The reaction mixture is heated slowly on a waterbath at 80° C. for 30 minutes. After cooling, a solution containing 0.61g (5.1×10⁻³ moles) of 3-bromoacetonitrile in 5 ml of DMF is slowly addedto the mixture. The latter is stirred for one hour at room temperatureand then it is poured into 100 ml of ice-cold water. A productprecipitates. After standing for 30 minutes, it is filtered, drained andthen recrystallized from ethanol. The compound (I-a8) has a meltingpoint of 136° C. The reaction yield is 59%.

Example 11: Preparation of the compound (I-a9):

4-(Benzyloxy)benzaldehyde acetyl(3-cyanopropyl)hydrazone

The compound (1-a9) is obtained by an alkylation reaction of4-(benzyloxy)benzaldehyde acetylhydrazone, prepared as described inpoint 9.1 of Example 9 above, with 4-bromobutyronitrile.

The alkylation reaction is performed according to a procedure identicalto that described in Example 10 above, with the aid of a solutioncontaining 0.75 g (5.1×10⁻³ moles) of 4-bromobutyronitrile in 5 ml ofDMF. It has a yield of 75%. The compound (I-a9) obtained has a meltingpoint of 103° C.

Example 12: Preparation of the compound (I-a10):

4-(Benzyloxy)benzaldehyde acetylpropargylhydrazone

This compound is obtained by an alkylation reaction of4-(benzyloxy)benzaldehyde acetylhydrazone, prepared as described inpoint 9.1 of Example 9, with propargyl bromide.

The alkylation reaction is performed according to a procedure identicalto that described in Example 10 above, with the aid of a solutioncontaining 0.60 g (5.1×10⁻³ moles) of propargyl bromide in 5 ml of DMF,with a yield of 54%. The compound (I-a10) has a melting point of 120° C.

Example 13: Preparation of the compound (I-b1): Benzaldehyde(2-cyanoethyl)(ethoxycarbonyl)hydrazone

13.1 Preparation of benzaldehyde (2-cyanoethyl)hydrazone:

Benzaldehyde (2-cyanoethyl)hydrazone is prepared using a procedureidentical to that described in point 1.1 of Example 1.

13.2 Acylation of benzaldehyde (2-cyanoethyl)hydrazone with ethylchloroformate:

1.08 g (10⁻² moles) of ethyl chloroformate in solution in 5 ml ofanhydrous ethyl acetate are added dropwise to a solution containing 10⁻²moles of benzaldehyde (2-cyanoethyl)hydrazone and 0.79 g (10⁻² moles) ofanhydrous pyridine in 20 ml of anhydrous ethyl acetate, with stirring inthe cold. The reaction mixture is slowly heated to reflux temperatureand left stirring for 2 hours and then filtered hot.

After cooling of the filtrate, the product crystallizes. It is filtered.An additional quantity of product may be obtained by evaporation of thefiltrate. The product is washed with 10 ml of water and then dried andrecrystallized from a mixture of ethyl acetate and petroleum ether. Ithas a melting point of 91° C. The reaction yield is 48%.

Example 14 Preparation of the compound (I-b2): 4-(Benzylozy)benzaldehyde(2-cyanoethyl)(ethoxycarbonyl)hydrazone

14.1 Preparation of 4-(benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone:

4-(Benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone is obtained accordingto a procedure identical to that described in point 2.1 of Example 2above.

14.2 Acylation of 4-(benzyloxy)benzaldehyde (2-cyanoethyl)hydrazone withethyl chloroformate:

It is carried out according to a procedure identical to that describedin point 13.2 of Example 13 above, starting with, on the one hand, asolution containing 10⁻² moles of 4-(benzyloxy)benzaldehyde(2-cyanoethyl)hydrazone and 0.79 g (10⁻² moles) of anhydrous pyridine in20 ml of anhydrous ethyl acetate and, on the other hand, a solutioncontaining 1.08 g (10⁻² moles) of ethyl chloroformate in 5 ml ofanhydrous ethyl acetate.

The product obtained is recrystallized from ethanol. The reaction yieldis 71%. The product has a melting point equal to 100° C.

Example 15: Preparation of the compound (I-b3): Benzaldehyde(2-hydroxyethyl)(ethoxycarbonyl)hydrazone

This compound is obtained by an acylation reaction of benzaldehyde(2-hydroxyethyl)hydrazone, prepared according to point 3.1 of Example 3,with ethyl chloroformate.

This acylation is performed in the following manner: 1.08 g (10⁻² moles)of ethyl chloroformate in 5 ml of anhydrous ethyl acetate are addeddropwise to a solution containing 10⁻² moles of benzaldehyde(2-hydroxyethyl)hydrazone and 0.79 g (10⁻² moles) of anhydrous pyridinein 20 ml of anhydrous ethyl acetate, with stirring in the cold. Thereaction mixture is left at 0° C. with stirring for 2 hours and then itis filtered. The product obtained is washed with 10 ml of water and thendried and recrystallized from a mixture of ethyl acetate and petroleumether. It has a melting point of 69.5° C. The reaction yield is 62%.

Example 16: Preparation of the compound (I-b4):4-(Benzyloxy)benzaldehyde (2-hydroxyethyl)(ethoxycarbonyl)hydrazone

This compound is obtained by an acylation reaction of4-(benzyloxy)benzaldehyde (2-hydroxyethyl)hydrazone, prepared accordingto point 4.1 of Example 4 above, with ethyl chloroformate.

The acylation reaction is carried out according to a procedure identicalto that described in Example 15 above, with the exception of therecrystallization of the product which is obtained from ethanol. Theyield of this acylation reaction is 71%. The product has a melting pointequal to 118° C.

Example 17: Preparation of the compound (I-c1): Benzaldehyde(2-cyanoethyl)(N-methylcarbamoyl)hydrazone

17.1 Preparation of benzaldehyde (2-cyanoethyl)hydrazone:

Benzaldehyde (2-cyanoethyl)hydrazone is obtained according to theprocedure described in point 1.1 of Example 1 above.

17.2 Acylation of benzaldehyde (2-cyanoethyl)hydrazone with methylisocyanate:

0.57 g (10⁻² moles) of methyl isocyanate is added, at 25° C., to asolution of 10⁻² moles of benzaldehyde (2-cyanoethyl)hydrazone in 30 mlof anhydrous benzene. The mixture is then heated to boiling temperatureand left under reflux for 30 minutes. On cooling, the acylated compoundcrystallizes. It is filtered, drained and then recrystallized from amixture of benzene and cyclohexane. Its melting point is 145° C. Thereaction yield is 48%.

Example 18: Preparation of the compounds (I-c2). (I-c3) and (I-c4):

The compounds (I-c2), (1-c3) and (I-c4) are obtained by an acylationreaction of respectively 4-(benzyloxy)benzaldehyde(2-cyanoothyl)hydrazone, benzaldehyde (2 -hydroxyethyl) hydrazone and4-(benzyloxy)benzaldehyde (2-hydroxyethyl)hydrazone, with methylisocyanate.

The (2-cyanoethyl)hydrazones and the (2-hydroxyethyl)hydrazones ofaromatic aldehydes are prepared according to points 2.1 of Example 2,3.1 of Example 3 and 4.1 of Example 4.

The acylation reaction of these hydrazones of aromatic aldehydes withmethyl isocyanate is carried out according to a procedure identical tothat described in point 17.2 of Example 17 above, except for therecrystallization of the compound (I-c4) which is obtained from ethanol.

The yield of this acylation is respectively:

41% for the compound (I-c2) 4-(benzyloxy)benzaldehyde(2-cyanoethyl)(N-methylcarbamoyl)hydrazone!, whose melting point is 152°C.,

35% for the compound (I-c3) benzaldehyde(2-hydroxyethyl)(N-methylcarbamoyl)hydrazone!, whose melting point is141.5° C.,

42% for the compound (I-c4) 4-(benzyloxy)benzaldehyde (2 -hydroxyethyl)(N-methylcarbamoyl) hydrazonel, whose melting point is 196° C.

Example 19: Preparation of the compounds (I-d1) and (I-d2):

The compounds (I-d1) and (I-d2) are prepared by an acylation reaction insitu performed according to the following procedure: 0.8 g (10⁻² moles)of (2-cyanoethyl)hydrazine is added to a solution of 1 g (10⁻² moles) ofbenzaldehyde (for the preparation of the compound (I-d1)) or of4-(benzyloxy)benzaldehyde (for the preparation of the compound (I-d2))in 30 ml of anhydrous benzene. The reaction mixture is heated to boilingtemperature until disappearance of the aldehyde, whose presence isdetected by thin-layer chromatography. The water is then removed byazootropic distillation. The solution is then cooled to 25° C. 1.3 g(1.1×10⁻² moles) of phenyl isocyanate are then added. The mixture isheated at boiling temperature for 5 minutes. A white product forms. Itis filtered and then washed with 5 ml of benzene. The recrystallizationof the product is performed in butanol.

The reaction yield is:

quantitative for the compound (I-d1) benzaldehyde(2-cyanoothyl)(N-phanylcarbamoyl)hydrazone!, whose melting point is 125°C.,

equal to 51% for the compound (I-d2) 4-(benzyloxy)benzaldehyde(2-cyanoethyl) (N-phenylcarbamoyl)hydrazone!, whose melting point is194° C.

Example 20: Preparation of the compound (I-e1):4-(Benzylozy)acetophenone acetyl(2-cyanoethyl)hydrazone

4.4×10⁻³ moles (0.37 g) of 2-(cyanoothyl)hydrazine are added, at roomtemperature and with stirring, to a solution containing 0.99 g (4.4×10⁻³moles) of 4-(benzyloxy)acetophenone in 20 ml of anhydrous benzene, inthe presence of a few drops of acetic acid. The reaction mixture isheated to reflux temperature and the water formed during the reaction isremoved by azeotropic distillation. The solution is then adjusted to 10°C. and 4.4×10⁻³ moles of anhydrous pyridine (0.34 g) and 4.4×10⁻³ molesof acetyl chloride (0.34 g) are added successively. The mixture is leftstirring at room temperature for 30 minutes. The benzene is then removedby evaporation under vacuum. The residue obtained is dissolved in 100 mlof dichloromethane and the resulting organic phase is washed three timeswith water. It is then dried over magnesium sulfate and then evaporated.The residue is recrystallized from ethanol. It has a melting point of77° C. The reaction yield is 15%.

Example 21: Pharmacological studies:

21.1 Activity and selectivity

The compounds of formula (I) were tested in vitro in order to determinetheir inhibitory activity toward rat brain MAO A and MAO B and theirselectivity toward these enzymes.

A/ Experimental procedure:

a) Preparation of the mitochondrial suspension:

* Collection of the cerebral tissues

Whistar rats weighing between 150 and 200 grams are killed bydecapitation. The brain, with the exception of the cerebellum, iscollected, weighed and homogenized using an Ultraturax (maximum speedfor 5 seconds, five times in succession) in a 0.32M sucrose and 10 mMTris buffer, pH 7.4 at 0° C., at the rate of 10 ml of buffer per gram offresh tissue.

* Preparation of the mitochondrial suspension

The homogenate obtained above is centrifuged for 5 minutes at 1000 g ina refrigerated centrifuge (+4° C.). The supernatant is recovered andsubjected to another centrifugation under the same conditions so as tocomplete the removal of vascular debris, of nuclei and of large myelinicfragments. A final centrifugation of the supernatant at 20,000 g, for 20minutes, makes it possible to obtain a pellet enriched in mitochondria.

The pellet is taken up in 100 mM (mono- and dipotassium) phosphatebuffer, pH 7.4, at the rate of 4 ml of buffer per gram of fresh tissue.

The enzymatic preparation thus obtained is fractionated into tubes atthe rate of 0.5 ml of solution per tube and stored at -80° C. A storageof a duration of a few months does not cause any loss of activity.

b) Assay of the monoamine oxidase (MAO) activity

* Principle of the measurement of the MAO enzymatic activity in vitro

Serotonin (5HT) and β-phenylethylamine (β-PEA), which constitute thesubstrates specific for MAO A and MAO B respectively, are used tomeasure each activity. These molecules are labeled on their side chainwith ¹⁴ carbon and are converted by the MAOs, by oxidative deamination,to 5-hydroxyindoleacetaldehyde and to β-phenylacetaldehyde respectively,according to the scheme below: ##STR7##

The mitochondria are incubated in the presence of one of the tworadioactive substrates. After a defined time, the enzymatic reaction isstopped by precipitation of the mitochondrial proteins. The radioactiveproducts are then extracted with a mixture of organic solvents. The MAOactivity is then determined by counting the radioactivity of theproducts of the reaction.

* Method of assay

The standard assay is performed with:

90 μl of 100 mM mono- and dipotassium phosphate buffer, of pH 7.4,

50 ml of mitochondrial suspension,

20 μl of H₂ O/DMSO mixture corresponding to the dilution of the productto be tested in the case of the control or 20 μl of a solution ofinhibitor to be tested at the chosen concentration,

40 μl of radioactive substrate with a radioactivity equal to 0.05 μCI,for a final volume of 200 μl.

The reaction necessary for the assay is performed either after apreincubation of the enzyme (MAO A or MAO B) with the inhibitor to betested, for a period of 30 minutes on a bath thermostated at 37° C., orwithout preincubation. In any case, the reaction is initiated by theaddition of 40 μl of a 10⁻⁵ molar solution of ¹⁴ carbon-labeled 5-HT (ofradioactive concentration=1.25 μCI/ml) or of a 5×10⁻⁶ molar solution of¹⁴ carbon-labeled β-PEA (of radioactive concentration=1.25 μCI/ml).

The incubation of the reaction mixture is maintained for 60 minutes for5-HT and 10 minutes for β-PEA, at the end of which the reaction isstopped by precipitation of the proteins by adding 200 ml of cold 4NHCl, and by immediately stirring the mixture obtained by means of avortex for 5 seconds.

The extraction of the products of the reaction is performed by theaddition of 1 ml of a mixture of toluene and ethyl acetate (1/1)followed by stirring on a vortex for 30 seconds and by centrifugation at3000 revolutions/minute for 5 minutes. 500 μl of supernatant arecollected and counted in 2 ml of toluene containing 0.4% diphenyloxazoleby means of a Rackseta 1290 whose yield is 94%.

The reaction blank consists in carrying out the procedure in the samemanner as for the standard test, but the substrate is added afterprecipitation of the mitochondrial proteins.

* Kinetic conditions for the assay

The enzymatic reactions are studied under the following conditions:

the concentration of the enzyme is substantially less than that of thesubstrates,

only the initial phase of the reaction is monitored.

These two conditions together set the framework of an enzymatic kineticmethod at the stationary phase of the reaction.

The residual activity of the enzyme is determined by the followingformula: ##EQU1##

* Determination of the protein concentration of the mitochondrialsuspension

It is performed with the aid of the assay kit Protein Assay Reagent fromthe company PIERCE CHEMICAL Co.

The optical density, read at the wavelength of 550 nm, is proportionalto the protein concentration of a biological sample.

The protein concentration of the mitochondrial suspension is determinedby comparison with a calibration series for bovine serum albumin dilutedin the mitochondria-suspending buffer.

FIG. 1 presents this calibration series, with, on the y-axis, theoptical density measured at 550 nm (OD 550 nm) and, on the x-axis, thebovine serum albumin (BSA) concentration expressed in mg/ml.

The mitochondrial suspension has an optical density equal to 0.238 at a1/15th dilution, and equal to 0.124 at a 1/30th dilution. The proteinconcentration is therefore 6 mg/ml. It is adjusted, by dilution, to aworking concentration of 0.6 mg/ml.

B/ Results:

The ICSO values for the inhibitors tested toward MAO A and MAO B, whichrepresent the inhibitory concentrations capable of obtaining a 50%inhibition of these enzymes, are determined graphically from the curvesof percentage residual activity of the MAOs for various concentrationsof inhibitors.

FIGS. 2 and 3 show, by way of examples, the curves of percentageresidual activity of MAO A and MAO B obtained with the compounds (I-a2)and (I-a4) respectively, on the one hand without preincubation of theenzyme and the compound (wp), on the other hand after preincubation ofthe enzyme and the inhibitor (ap). The percentage of residual enzymaticactivity is expressed on the y-axis and the logarithm in base 10 of theconcentration of inhibitor is expressed on the x-axis.

Table 2 presents the IC₅₀ values, expressed in moles/liter, toward MAO Aand toward MAO B, of various compounds of formula (I), which values areobtained, on the one hand, without preincubation of the enzyme and thecompound and, on the other hand, with preincubation of the enzyme andthe inhibitor.

                  TABLE 2                                                         ______________________________________                                                             IC.sub.50 MAO A                                                                           IC.sub.50 MAO B                              Code No.             (M)         (M)                                          ______________________________________                                        I-a2     wp          nd          3.5 × 10.sup.-8                                 ap          nd          3 × 10.sup.-9                          I-a2.1   wp          nd          4.3 × 10.sup.-5                                 ap          nd          6.9 × 10.sup.-7                        I-a2.2   wp          nd          3 × 10.sup.-6                                   ap          nd          1.4 × 10.sup.-6                        I-a2.3   wp          nd          1.13 × 10.sup.-5                       22       ap          nd          2.45 × 10.sup.-7                       I-a2.4   wp          nd          2.8 × 10.sup.-5                                 ap          nd          2.15 × 10.sup.-6                       I-a2.5   wp          nd          precipitate                                           ap          nd          3.8 × 10.sup.-7                        I-a4     wp          5 × 10.sup.-5                                                                       2.8 × 10.sup.-8                                 ap          5 × 10.sup.-5                                                                       6.3 × 10.sup.-9                        I-a6     wp          5.3 × 10.sup.-5                                                                     3 × 10.sup.-6                                   ap          6.8 × 10.sup.-6                                                                     1.5 × 10.sup.-8                        I-a10    wp          nd          4.1 × 10.sup.-6                                 ap          nd          3.6 × 10.sup.-7                        I-b2     wp          nd          2.2 × 10.sup.-5                                 ap          nd          6.3 × 10.sup.-6                        I-b4     wp          nd          3.5 × 10.sup.-5                                 ap          nd          10.sup.-5                                    I-c1     wp          nd          2.8 × 10.sup.-4                                 ap          nd          1.2 × 10.sup.-4                        I-c2     wp          nd          1.8 × 10.sup.-6                                 ap          nd          2.5 × 10.sup.-6                        ______________________________________                                         wp: without preincubation                                                     ap: after preincubation                                                       nd: not determinable, excessively weak inhibition                        

21.2 Reversibility of the inhibitory activity toward the MAO BEs

The reversibility of the inhibitory activity of the compounds of formula(I) is determined by comparing the percentages of residual activity ofmonoamine oxidase B, which are obtained before and after washing amixture of enzyme and inhibitor previously subjected to incubation for aperiod of 30 minutes at 37° C.

A/ Principle:

The enzyme, in solution in phosphate buffer, and the inhibitor areincubated for 30 minutes at 37° C. At the end of this incubation, aproportion of the solution is subjected to a test of activity asdescribed below, which makes it possible to determine the percentages ofenzymatic activity before washing of the enzyme+inhibitor solution. Therest of the solution is diluted 10-fold with phosphate buffer and thencentrifuged for 20 minutes at 27,000 g in a refrigerated centrifuge. Thesupernatants are removed. The pellets are taken up in a volume ofphosphate buffer corresponding to the quantity of supernatant removed.Centrifugation is performed under the same conditions as above. Thesupernatants are removed. The pellets are again taken up in a volume ofphosphate buffer equal to the volume of supernatant removed.Centrifugation is again performed and the pellets are taken up in theminimum quantity of phosphate buffer necessary for the activity test,which makes it possible to define the percentages of enzymatic activityafter washing the enzyme+inhibitor solution.

Deprenyl, an irreversible inhibitor of MAO B, serves as referenceproduct.

A control is prepared using 1% DMSO (dimethyl sulfoxide) in place of theinhibitor.

B/ Test of activity:

Each test is performed with:

160 μl of solution containing MAO B and the inhibitor or DMSO inphosphate buffer,

40 μl of a 5 μM solution of ¹⁴ carbon-labeled β-phenylethylamine(radioactivity=0.25 μCi).

The reaction is initiated by adding the 40 μl of β-phenylethylamine. Thereaction time is one minute. The reaction is stopped by addition of 200μl of 4N HCl and then 1 ml of a mixture of ethyl acetate and toluene(1/1) is added in order to extract the radioactive product. The tubesare centrifuged for 5 minutes at 3000 revolutions per minute in arefrigerated centrifuge. 2 ml of scintillant are added to 500 μl ofsupernatant directly in the tubes. The counting is performed over 120seconds.

C/ Results:

Table 3 presents the mean percentages of residual MAO activity which areobtained from 4 assays, for the compound (I-a2) and deprenyl, before andafter washing the enzyme+inhibitor mixture.

                  TABLE 3                                                         ______________________________________                                                    Percentage of residual MAO activity                               Inhibitor     Before washing                                                                           After washing                                        ______________________________________                                        Compound (I-a2)                                                                             14         105                                                  Deprenyl      25.6%      14.7%                                                ______________________________________                                    

FIG. 4 shows, in the form of three histograms, the results of Table 3 aswell as the loss of enzymatic activity linked to time. The percentage ofresidual enzymatic activity is expressed on the y-axis.

The first histogram corresponds to the mean percentages of residual MAOactivity which are obtained with the control (C), deprenyl (D) and thecompound (I-a2), respectively, before washing the mixture. The secondhistogram corresponds to the mean percentages of residual MAO activitywhich are obtained with the control (C), deprenyl (D) and the compound(I-a2), respectively, after washing the mixture. The third histogramshows, for the control and the inhibitors tested, the loss of enzymaticactivity linked to time.

21.3 Toxicity

The evaluation of the cytotoxicity of the compounds of formula (I) wasthe subject of two different tests:

an MTT test (3- 4,5-dimethylthiazol-2-yl!-2,5-diphenyltetrazoliumbromide) on adherent cells,

a test on the cells in suspension.

A/ KTT test on adherent calls:

Epithelial cells, Hela Ohio, are used. This cell line is derived from ahuman cervical cancer. The cells are cultured in EMEM mediumsupplemented with 10% fetal calf serum.

The compounds in accordance with the invention are tested atconcentrations of between 10⁻⁴ and 10⁻⁸ molar in 75% DMSO.

In a 96-well plate, 3×10⁴ Bela cells in 100 μl of culture medium aredeposited per well. The plates are incubated for 18 hours, at atemperature of 37° C., in a humid atmosphere with 5% CO₂. The cells canthus adhere to their support. A solution of compound to be tested, witha concentration of between 10⁻⁴ and 10⁻⁸ molar or a 75% solution of DMSOintended to obtain growth controls, is added to the wells.

After incubating for a period of 24 hours, in a humid atmosphere, with5% CO₂, the cells are washed with PBS. 10 μl of a solution containing 5mg/ml of MTT in PBS are then added with 100 μl of medium to each well.The plates are incubated for 4 hours at 37° C. in a humid atmosphere andwith 5% CO₂. MTT is metabolized in the live cells to an insoluble purplecompound. At the end of the incubation, the wells are washed with PBS inorder to remove the MTT in suspension. 100 μl of DMSO, added to thewells, cause lysis of the cells and the solubilization of the coloredproduct. The plates are stirred for 15 minutes in order to homogenizethe medium and the suspension of purple product. The concentration ofthe metabolite in the wells is read by photometry at a wavelength of 550nm and the number of live cells is a function of the optical densityobtained. The viability index is calculated thus: ##EQU2##

OD_(t) being the optical density obtained for cells treated with DMSOand OD being the optical density for the cells treated with a compoundin accordance with the invention.

B/ Test performed on the cells in suspension:

Daudi cells are used. This cell line is derived from a human Burkitt'slymphoma. The cells are cultured in an RPMI medium supplemented with 10%fetal calf serum.

The compounds in accordance with the invention are used atconcentrations of between 10⁻⁴ and 10⁻⁸ molar in 75% DMSO.

Each well of a 24-well plate is inoculated with 100 μl of a cellsuspension containing 2×10⁵ cells per ml. Each well receives a compoundto be tested, at a concentration of between 10⁻⁴ and 10⁻⁸ molar or 75%DMSO (growth controls).

The plates are incubated for 24 hours at 37° C., in a humid atmosphereand with 5% CO₂. After homogenization of the medium, 100 ml ofsuspension are collected from the well and mixed with 100 ml of Trypanblue at 0.04% in PBS. The Trypan blue diffuses in the dead cells but notin the live cells.

The live (refringent) and dead (blue) cells are counted on a Malassezcell. The live cell fraction (Lf) is equal to the ratio of the number oflive cells to the total number of cells. The viability index is equalto: ##EQU3##

Lft being the live fraction of the cells treated with DMSO and Lf beingthe live fraction of cells treated with the compounds in accordance withthe invention.

C/ Results:

Table 4 below presents the results of the cytotoxicity tests performedwith compounds of formula (I). Two values were retained for each type oftest:

* the lethal dose (50 LD50) corresponding to the concentration,expressed in moles/liter, of compound for which 50% of the cells arekilled.

* the maximum concentration of compound (MC100), expressed inmoles/liter, for which all the cells are alive.

                  TABLE 4                                                         ______________________________________                                                MTT test on adherent                                                                          Test on cells in                                      Code    cells           suspension                                            No.     LD50 (M) MC100 (M)  LD50 (M)                                                                             MC100 (M)                                  ______________________________________                                        I-a2    10.sup.-4                                                                              10.sup.-5  10.sup.-4                                                                            10.sup.-5                                  I-a2.2  3 × 10.sup.-5                                                                    6.5 × 10.sup.-7                                                                    2.2 × 10.sup.-5                                                                10.sup.-5                                  I-a2.3  2.2 × 10.sup.5                                                                   6 × 10.sup.-7                                                                      5 × 10.sup.-5                                                                  10.sup.-5                                  I-a2.4  4 × 10.sup.-5                                                                    2.3 × 10.sup.-6                                                                    6.5 × 10.sup.-5                                                                1.25 × 10.sup.-5                     I-a4    10.sup.-4                                                                              10.sup.-5  10.sup.-4                                                                            10.sup.-5                                  ______________________________________                                    

We claim:
 1. A method of selectively inhibiting monoamine oxidase Bactivity in a human or an animal, which method comprises administeringto said human or said animal an effective amount of a compound offormula (I): ##STR8## in which: R₁ represents a hydrogen atom, abenzyloxy group or a phenylethoxy group whose phenyl ring is optionallysubstituted;p is an integer from 0 to 3; R₃ represents a hydrogen atom,a CN group, a hydroxyl group, a CCH group, a (C₁ -C₃ alkoxy) carbonylgroup or a C₁ -C₃ alkylated cyanomethyl group; R₂ represents a hydrogenatom or a C₁ -C₃ alkyl group; n is equal to 0 or 1, in which case:ifn=0, R₄ represents a C₁ -C₃ alkyl group or a C₁ -C₃ alkoxy group;whereas if n=1, y=1 and R₄ represents a C₁ -C₃ alkyl group, a C₁ -C₃alkoxy group or a phenyl group.
 2. The method as claimed in claim 1,wherein R₁ represents a benzyloxy group whose phenyl ring is optionallysubstituted with one or more halogen atoms and/or one or more NO₂ groupsand/or one or more C₁ -C₃ alkyl groups and/or one or more C₁ -C₃ alkoxygroups.
 3. The method as claimed in claim 1 or claim 2, wherein thecompound is selected from the group consistingof:4-(benzyloxy)benzaldehyde acetyl(2-cyanoethyl)hydrazone, 4-(4-methylbenzyl)oxy!benzaldehyde acetyl (2-cyanoethyl)hydrazonc(I-a2.1)!, 4- (4-nitrobenzyl)oxy!benzaldehydeacetyl(2-cyanoethyl)hydrazonc (I-a2.2)!, 4-(4-chlorobenzyl)oxy!benzaldehyde acetyl(2-cyanoathyl)hydrazonc(I-a2.3)!, 4- (4-methoxybenzyl)oxy!benzaldehydcacetyl(2-cyanoethyl)hydrazonc (I-a2.4)!, 4-(2,4-ditlalorobenzyl)oxy!benzaldehyde acetyl(2-cyanoethyl)hydrazone(I-a2.5)!, 4- 2-chlorobenzyl)oxy!benzaldehyde acctyl(2-cyanoethyl)hydrazone (I a2.6)!, 4-(benzyloxy)benzaldehydeacetyl(2-hydroxyethyl)hydrazone (I-a4)!, 4-(benzyloxy)benzaldehydeacetyl (2-methoxycarbonyl-ethyl)hydrazone (I-a5!,4-(2-phenylcthoxy)benzaldehyde acetyl(2-cyanoethyl)hydrazone (I-a6)!,4-(benzyloxy)benzaldehyde acetyl (2-cyanopropyl)hydrazone (I-a7)!,4-(benzyloxy)benzaldehyde acetyl(cyanomethyl)hydrazone (I-a8)!,4-(benzyloxy)benzaldehyde acetyl (3 -cyanopropyl)hydrazone (I-a9)!,4-(benzyloxy)benzaldehyde acetylpropargylhydrazone (I-a10)!, 4(benzyloxy) benzaldehyde(2-cyanoethyl) (ethoxycarbonyl)hydrazone(I-b2)!, 4-(benzyloxy)benzaldehyde(2-hydroxyethyl)(ethoxycarbonyl)hydrazone (I-b4)!, benzaldehyde(2-cyanoethyl)(N-methylcarbamoyl)hydrazone (I-c1)!,4-(benzyloxy)benzaldehyde(2-cyanoethyl) (N-methylcarbamoyl)hydrazone(I-c2)!, benzaldehyde(2-cyanoethyl) (N-phenylcarbamoyl)hydrazone(I-d1)!, 4-(benzyloxy)benzaldehyde(2-cyanoethyl)(N-phenylcarbamoyl)hydrazone (T-d2)!, and 4-(benzyloxy)acetophenoneacetyl (2-cyanoethyl)hydrazone (I-e1)!.
 4. A compound selected from thegroup consisting of compounds having the following specific formulae:##STR9## in which: R₁ represents a hydrogen atom, a benzyloxy group or aphenylethoxy group whose phenyl ring is optionally substituted, providedthat R₁ is different from a hydrogen atom in the specific formula(I-e);p is an integer from 0 to 3; and R₃ represents a CN group, an OHgroup, a CCH group, a (C₁ -C₃ alkoxy) carbonyl group or a C₁ -C₃alkylated cyanomethyl group.
 5. The compound as claimed in claim 4,selected from the group consisting of:benzaldehyde(2-cyanoethyl)(N-phenylcarbamoyl)hydrazone (I-d1)!,4-(benzyloxy)benzaldehyde(2-cyanoethyl) (N-phenylcarbamoyl)hydrazone (Id2)!, and 4-(benzyloxy)acetophenone acetyl (2-cyanoethyl)hydrazone(I-e1)!.
 6. A process for the preparation of a compound of formula (I-d)##STR10## which comprises: reacting an aromatic aldehyde of formula:##STR11## in which: R₁ represents a hydrogen atom, a benzyloxy orphenylethoxy group whose phenyl ring is optionally substituted, and ahydrazine of formula: NH₂ --NH--(CH₂)_(p) --R₃ in which:p is an integerfrom 0 to 3; R₃ represents a CN group, an OH group, a CCH group, a (C₁--C₃ alkoxy)carbonyl group or a C₁ --C₃ alkylated cyanomethyl group toform a condensation product; and acylating the condensation product toform a compound of formula (I-d).
 7. A process for the preparation of acompound of specific formula (I-e) ##STR12## which comprises: reactingan aromatic aldehyde of formula: ##STR13## in which: R₁ represents abenzyloxy or phenylethoxy group whose phenyl ring is optionallysubstituted; and:a hydrazine of formula: NH₂ --NH--(CH₂)_(p) --R₃ inwhich: p is an integer from 0 to 3; R₃ represents a CN group, an OHgroup, a CCH group, a (C₁ --C₃ alkoxy)carbonyl group or a C₁ --C₃alkylated cyanomethyl group;or a hydrazine of formula: NH₂ --NH--CO--CH₃to form a condensation product; and acylating the condensation productor alkylating the condensation product using a reagent of formula:Hal--(CH₂)_(p) --C.tbd.Z in which: p is an integer from 0 to 3; Halrepresents a halogen atom; Z represents a CH group or a nitrogen atom,or by a reagent of formula: Br--(CH₂)_(p) --COO--(C₁ -C₃ alkyl) in whichp is an integer from 0 to 3 to form a compound of formula (I-e).
 8. Themethod as claimed in claim 3, wherein the compound is4(benzyloxy)-benzaldehyde acetyl(2-cyanoethyl) hydrazone (I-a2)!.
 9. Themethod as claimed in claim 3, wherein the compound is benzaldehyde(2-cyanoethyl(N-phenyl-carbamoyl)hydrazone (I-d1)!.
 10. The method asclaimed in claim 3, wherein the compound is 4-(benzyloxy)benzaldehyde(2-cyanoethyl)-(N-phenylcarbamoyl)hydrazone (I -d2)!.
 11. The method asclaimed in claim 3, wherein the compound is 4-(benzyloxy)acetophenoneacetyl(2-cyano-ethyl)hydrazone (I-31)!.
 12. The method as claimed inclaim 6, wherein said step of acylating the condensation productcomprises acylating the condensation product using phenyl isocyanate.13. The method as claimed in claim 7, wherein said step of acylating thecondensation product comprises acylating the condensation product usingan acid chloride.